Timing Analysis of the 2022 Outburst of the Accreting Millisecond X-Ray Pulsar SAX J1808.4-3658: Hints of an Orbital Shrinking

We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of ≃1 × 1036 erg s-1 in about a week, the pulsar entered a ~1 month long reflaring stage. Comparison of the average pulsar spin frequency during the outburst with those previously measured confirmed the long-term spin derivative of ν˙SD=−(1.15±0.06)×10−15 Hz s-1, compatible with the spin-down torque of a ≈1026 G cm3 rotating magnetic dipole. For the first time in the last twenty years, the orbital phase evolution shows evidence for a decrease of the orbital period. The long-term behavior of the orbit is dominated by an ~11 s modulation of the orbital phase epoch consistent with a ~21 yr period. We discuss the observed evolution in terms of a coupling between the orbit and variations in the mass quadrupole of the companion star

Random-Matrix Theory of Quantum Transport

This is a comprehensive review of the random-matrix approach to the theory of phase-coherent conduction in mesocopic systems. The theory is applied to a variety of physical phenomena in quantum dots and disordered wires, including universal conductance fluctuations, weak localization, Coulomb blockade, sub-Poissonian shot noise, reflectionless tunneling into a superconductor, and giant conductance oscillations in a Josephson junction.Comment: 85 pages including 52 figures, to be published in Rev.Mod.Phy

A new integrated approach to improve left ventricular electromechanical activation during right ventricular septal pacing

Aims The deleterious effects of apical right ventricular pacing has fostered the utilization of alternative pacing sites. Although right ventricular septal (RVS) sites are commonly used, the results have been controversial because of poor standardization of lead position by fluoroscopy. This study investigated the utility of a new RVS pacing technique based on the combination of fluoroscopy (F), and electrophysiological mapping (F + EP). Left ventricular (LV) electromechanical activation was determined in patients undergoing RVS pacing and the results of the F + EP approach were compared with those derived from standard F alone. Methods and results Between December 2008 and November 2010 we enrolled 156 consecutive patients undergoing permanent RVS pacing. The standard F approach was used in 93 patients and the F + EP technique was applied to 63 patients. Electromechanical activation was assessed by: (i) electromechanical latency (EML) interval measured from the QRS onset to the mechanical activation of the basal LV and (ii) intra-LV dyssynchrony measured as the interval from the earliest to the latest LV basal motion. Intra-LV dyssynchrony was found in 46.2% patients in the F group compared with 15.9% in the group F + EP (P < 0.001). The F group demonstrated a significantly higher degree of intra-LV dyssynchrony than F + EP group (43.9 +/- 24.3 vs. 26.5 +/- 15.4 ms; P < 0.001). The F group exhibited a significantly higher EML duration compared with the F + EP group (215.8 +/- 25.3 vs. 195.1 +/- 17.4 ms; P < 0.001). Conclusion During RVS pacing, the F + EP approach provides a more physiological LV activation than the standard F technique. The prognostic significance of these short-term findings needs to be correlated with long-term data

Timing analysis of the 2022 outburst of the accreting millisecond x-ray pulsar SAX J1808.4-3658: hints of an orbital shrinking

We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4−3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of ≃1 × 1036 erg s−1 in about a week, the pulsar entered a ∼1 month long reflaring stage. Comparison of the average pulsar spin frequency during the outburst with those previously measured confirmed the long-term spin derivative of Hz s−1, compatible with the spin-down torque of a ≈1026 G cm3 rotating magnetic dipole. For the first time in the last twenty years, the orbital phase evolution shows evidence for a decrease of the orbital period. The long-term behavior of the orbit is dominated by an ∼11 s modulation of the orbital phase epoch consistent with a ∼21 yr period. We discuss the observed evolution in terms of a coupling between the orbit and variations in the mass quadrupole of the companion star

Timing Analysis of the 2022 Outburst of the Accreting Millisecond X-Ray Pulsar SAX J1808.4-3658: Hints of an Orbital Shrinking

We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4−3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of ≃1 × 10 ^36 erg s ^−1 in about a week, the pulsar entered a ∼1 month long reflaring stage. Comparison of the average pulsar spin frequency during the outburst with those previously measured confirmed the long-term spin derivative of ${\dot{\nu }}_{\mathrm{SD}}=-(1.15\,\pm \,0.06)\times \,{10}^{-15}$ Hz s ^−1 , compatible with the spin-down torque of a ≈10 ^26 G cm ^3 rotating magnetic dipole. For the first time in the last twenty years, the orbital phase evolution shows evidence for a decrease of the orbital period. The long-term behavior of the orbit is dominated by an ∼11 s modulation of the orbital phase epoch consistent with a ∼21 yr period. We discuss the observed evolution in terms of a coupling between the orbit and variations in the mass quadrupole of the companion star

Immunological history governs human stem cell memory CD4 heterogeneity via the Wnt signaling pathway

10.1038/s41467-020-14442-6Nature Communications11182